RFX1 is identical to enhancer factor C and functions as a transactivator of the hepatitis B virus enhancer
RFX1 is identical to enhancer factor C and functions as a transactivator of the hepatitis B virus enhancer
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DOI：
10.1128/mcb.13.10.6375-6384.1993
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发表时间：
1993-10
影响因子：
5.3
通讯作者：
C. Siegrist;B. Durand;P. Emery;E. David;P. Hearing;B. Mach;W. Reith
中科院分区：
文献类型：
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作者：
C. Siegrist;B. Durand;P. Emery;E. David;P. Hearing;B. Mach;W. Reith
乙型肝炎病毒基因表达在很大程度上受增强子 I (EnhI) 的控制。 EnhI 的活性严格依赖于增强子因子 C (EF-C) 位点，这是一种反向重复序列，与普遍存在的核蛋白 EF-C 结合。在这里，我们报告了一个意想不到的发现，即 EF-C 实际上与 RFX1 相同，RFX1 是一种先前通过其与 HLA II 类 X-box 启动子元件的亲和力而克隆的新型转录因子。这一发现使我们能够提供直接证据，证明 RFX1 (EF-C) 对于 HepG2 肝癌细胞中的 EnhI 功能至关重要； RFX1 特异性反义寡核苷酸似乎可以抑制 EnhI 驱动的乙型肝炎病毒主要表面抗原基因的表达，并且在转染测定中，RFX1 充当 EnhI 的有效反式激活因子。有趣的是，在非肝脏来源的细胞系中没有观察到 RFX1 (EF-C) 对 EnhI 的反式激活，这表明普遍存在的 RFX1 蛋白与肝脏特异性因子协同作用。
Hepatitis B virus gene expression is to a large extent under the control of enhancer I (EnhI). The activity of EnhI is strictly dependent on the enhancer factor C (EF-C) site, an inverted repeat that is bound by a ubiquitous nuclear protein known as EF-C. Here we report the unexpected finding that EF-C is in fact identical to RFX1, a novel transcription factor previously cloned by virtue of its affinity for the HLA class II X-box promoter element. This finding has allowed us to provide direct evidence that RFX1 (EF-C) is crucial for EnhI function in HepG2 hepatoma cells; RFX1-specific antisense oligonucleotides appear to inhibit EnhI-driven expression of the hepatitis B virus major surface antigen gene, and in transfection assays, RFX1 behaves as a potent transactivator of EnhI. Interestingly, transactivation of EnhI by RFX1 (EF-C) is not observed in cell lines that are not of liver origin, suggesting that the ubiquitous RFX1 protein cooperates with liver-specific factors.